Isaac approaching hurricane strength

By: Angela Fritz , 9:14 PM GMT on August 27, 2012

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Isaac is walking the line of hurricane status this afternoon after a hurricane hunter mission investigated the storm and found winds of 80+ mph with the SFMR instrument, which looks down at the surface from the plane and estimates what wind speeds are. This instrument has a notoriously rough time in doing so when there's heavy rain, and since the strongest winds were recorded coinciding with the strongest rain, you can imagine that this region of high wind speed could be suspect. The hurricane hunter mission is still in the storm, so I imagine they will issue a special update if needed. Currently the best estimate of wind speed within the storm is 70 mph. Isaac's pressure has been dropping today as well and is now 981 mb. Isaac is moving northwest at 12 mph--no change since this morning. Satellite loops show that Isaac remains large, though asymmetric, with most of the strong thunderstorm activity on the west and southwest side. Isaac's southeast side continues to struggle with dry air and wind shear, which could help to moderate Isaac's intensity as it approaches the coast.

An oil platform in the northern Gulf of Mexico is reporting sustained winds from the north-northeast at 40 mph this afternoon. A buoy west of Tampa, Florida is recording sustained winds around 30 mph, and platforms south of Louisiana are recording winds from 35-40 mph. The widespread heavy rain of yesterday has lightened up in Florida, but a strong line of thunderstorms in one of Isaac's outer bands is training northward along and offshore of the east coast of Florida, affecting everyone from Miami to Jacksonville.

This afternoon the AP reported that Isaac's death toll in Haiti jumped to 19, which puts Isaac's total death count at 21. It appears most of the deaths in Haiti were due to collapsing structures.


Figure 1. Satellite imagery of Tropical Storm Isaac around 3pm EDT on Monday.

Track forecast:
Models seem to be coming into better agreement today on where Isaac will make landfall, closing in on Louisiana and New Orleans as most likely landfall point. The ECMWF, HWRF, and UKMET all suggest New Orleans as the landfall location. The GFS is only slightly west of that. The GFDL is the farthest west, predicting landfall near the Louisiana-Texas border. Landfall timing remains Tuesday night. Beyond landfall, Isaac is expected to move north toward the Midwest through the rest of this week, however, models are showing that the system will likely slow down around landfall time, prolonging impacts like surge and inland flooding.

Intensity forecast:
The closer Isaac gets to landfall without having formed an eye, the better it is for intensity at landfall. Isaac has strengthened only modestly in the past 24 hours, and is still struggling with a less-than-conducive atmospheric environment. The HWRF remains on the high end of the intensity spectrum, suggesting Isaac will be a weak category 2 upon landfall. Other models suggest it will be a strong category 1, but the difference is splitting hairs. The National Hurricane Center's official forecast is for Isaac to continue strengthening over the next day, reaching category 2 at landfall.


Figure 2. Tide gauge data from St. Petersburg, Florida. The green line shows the storm surge. As Isaac's counterclockwise winds blew offshore this morning, water levels feel two feet at St. Petersburg. The winds switched to onshore this afternoon as the center of Isaac moved more to the northwest, bringing a storm surge of two feet to the city.

Storm surge observations from Isaac
This morning, as Isaac's counter-clockwise winds brought offshore winds to the Tampa/St. Petersburg area, ocean waters fell two feet along the coast. This afternoon, winds have shifted to blow onshore, and a two foot storm surge has been observed at Naples, Fort Meyers, and St. Petersburg on the west coast of Florida. Water levels have also begun to rise along the coast of Louisiana, with a storm surge of 1.5 feet already occurring at Shell Beach on the east side of New Orleans in Lake Borgne.

Angela and Jeff

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Quoting wxchaser97:
Still at 54 hours at Huffman's site, really wanted to know what the gfs had to say about future Kirk.


GFS is delayed.
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Quoting moonlightcowboy:


Mobile is still a possibility, tennisgirl! If he takes off a bit, sure could come northwards fairly quickly with the inland high getting weaker. Stay safe!
Quoting moonlightcowboy:


Mobile is still a possibility, tennisgirl! If he takes off a bit, sure could come northwards fairly quickly with the inland high getting weaker. Stay safe!



Thanks. Concerned about that
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Storm has literally been slapped back into the gulf.
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I'm seriously waiting for the winds to catch up, it has to happen.
Member Since: June 17, 2011 Posts: 11 Comments: 6541
Still at 54 hours at Huffman's site, really wanted to know what the gfs had to say about future Kirk.
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1999. KEEPEROFTHEGATE (Mod)


took a little nap to awaken to a much more southerly approach
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1998. Scotth
Quoting Beachfoxx:
Strange that the best two days of the past 6 weeks are the last two while we have Isaac out there!
I don't ever remember a summer as wet as this one here on the Emerald Coast....

OK - Poof!
I'm really gone now. TTYL


Good night BF
Member Since: August 4, 2004 Posts: 0 Comments: 23
Isaac continues on a heading of 290 degrees or west-northwest!
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MLC - BTW, are you wishcasting Isaac my way and away from you? LOL..
Member Since: August 3, 2006 Posts: 133 Comments: 20649
GFS Model Status

NOUS42 KWNO 280420
ADMNFD
SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
0419Z TUE AUG 28 2012
THE 00Z GFS FORECAST IS RUNNING LONGER THAN USUAL AFTER 54
HOURS...EXPECT SOME DELAYS IN PRODUCTS AFTER 54 HOURS...AT THIS
POINT THE OUTPUT IS RUNNING APPROXIMATELY 25 MINUTES LATE...
OREILLY/SDM/NCO/NCEP
Member Since: Posts: Comments:
Quoting AllyBama:


got it on speed dial - lol...

I am reading the chatter about west vs east and yes I realize that - NOW convincing hubby and others of this possibly is useless at this point..I love to see them all eat crow..:-))


How far East?
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hi all i have been on here since Rita...I feel as if I know a lot of you.. You yell at each other as if you were sitting down for a family dinner. Yelling always gets the point across in my house also. I live in Sulphur,La. My father was retired Navy Chief so we have always lived by one coast or the other.

But what I was saying I have enjoyed listening to each of you over he yrs.I have learned a lot from all of you.
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Quoting tennisgirl08:


?? I'm in Bama


Mobile is still a possibility, tennisgirl! If he takes off a bit, sure could come northwards fairly quickly with the inland high getting weaker. Stay safe!
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why is the gfs initialized at 991 mb instead of 979 mb
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Quoting moonlightcowboy:
Ally, if you're still up listening to the Divinyls still a chance this thing can bend your way.


got it on speed dial - lol...

I am reading the chatter about west vs east and yes I realize that - NOW convincing hubby and others of this possibly is useless at this point..I love to see them all eat crow..:-))
Member Since: August 3, 2006 Posts: 133 Comments: 20649
Quoting stormchaser19:


YES HERE IN ALLAN HUFFMAN´S


NCEP is stuck at 54 hours too.
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1988. will40
Quoting Beachfoxx:
Strange that the best two days of the past 6 weeks are the last two while we have Isaac out there!
I don't ever remember a summer as wet as this one here on the Emerald Coast....

OK - Poof!
I'm really gone now. TTYL


ni ni Beachy
Member Since: September 19, 2005 Posts: 2 Comments: 4266
Strange that the best two days of the past 6 weeks are the last two while we have Isaac out there!
I don't ever remember a summer as wet as this one here on the Emerald Coast....

OK - Poof!
I'm really gone now. TTYL
Quoting WXGulfBreeze:


Meh - we had 15" with a lot of flooding a few months back, and had a line of thunderstorms through here recently that clocked north of 80MPH winds. It's been doing nothing but raining here for the past month, almost every day. The past couple of days of sunshine and no rain have been very pleasurable.
Member Since: July 10, 2005 Posts: 157 Comments: 29391
Quoting mynameispaul:


Yes, three days of that for me. Purple.
Member Since: June 16, 2006 Posts: 0 Comments: 1588
Quoting moonlightcowboy:
Ally, if you're still up listening to the Divinyls still a chance this thing can bend your way.


?? I'm in Bama
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Dropsonde also shows 979mb pressure, waiting for the VDM for the winds speeds.
Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
979mb (28.91 inHg) Sea Level (Surface) 27.4°C (81.3°F) 27.3°C (81.1°F) 280° (from the W) 4 knots (5 mph)
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Member Since: Posts: Comments:
979mb (28.91 inHg) Sea Level (Surface)
Dropsonde Location: Dropped in eye.
Member Since: September 7, 2006 Posts: 91 Comments: 2692
Quoting Orcasystems:


highest I saw on the last inbound run from the west was 59.9 mph
ok good. that's a better sounding number.
Member Since: August 28, 2005 Posts: 0 Comments: 153
I'm going to sleep.

I may wake up with bad weather already, though nothing's going on right now.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting chicagowatcher:
HH find 78 mph winds? thought I saw that reported, but didn't see it all and maybe that wasn't surface?


highest I saw on the last inbound run from the west was 59.9 mph
Member Since: October 1, 2007 Posts: 81 Comments: 26516
1978. Michfan




3 hours old.
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Ally, if you're still up listening to the Divinyls still a chance this thing can bend your way.
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1976. Scotth
Quoting wxchaser97:

Still looks like a WNW/NW motion to me and recon fix shows a WNW movement(293 degrees).


Right side is reforming. Almost looks like it wants to pull the rest of the storm into the right side of the storm. Its definitely changing its weird shape and looking like its going for more rounded appearance.
Member Since: August 4, 2004 Posts: 0 Comments: 23
Quoting ih8hurricanes:
Sat loop looks more wnw than w to my untrained eyes.

Thats because Isaac is moving WNW right now.
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1974. Ryuujin
Quoting CaicosRetiredSailor:


Another EYE!

/sarcasm
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Quoting Orcasystems:


Agreed :)

Member Since: August 23, 2012


Not sure what that means...flycasting...but your point of me being a newbie is misinformed - my old handle was a location in Texas, I now live in Alabama, and couldn't figure out how to change it...

Thus - I had to create a new one this past week.

Original join was in 2004 I think for Ivan.

I mostly lurk...typically only log in when a storm is on my doorstep.

I find some of the graphics that several posters post hands down the best anywhere...some people have great opinions, some are just silly.

Glad there is such a tight community here, not trying to encroach.

This is not a met post so I will button up...but just wanted to explain...
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Sat loop looks more wnw than w to my untrained eyes.
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just tossen this up but how about a center relocate?
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Good Night All - Stay Safe - Sleep Well
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1969. Michfan
Looks like that dry air slot prevented it from bombing out. Good thing for New Orleans.
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I know this has been said before but Isaac looks like a Wpac tropical cyclone right now.
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1967. jake436
Quoting BABYGURL:
Oh This suspense of the storm is terrible. We are bunkered down at the top of Plaquemines Parish in Lousiana right below New Orleans. Praying all the prep work done by the Core and our Parish Pres. Billy Nungessor hold up!
Where are you? Belle Chasse?
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1966. will40
Quoting BABYGURL:
Oh This suspense of the storm is terrible. We are bunkered down at the top of Plaquemines Parish in Lousiana right below New Orleans. Praying all the prep work done by the Core and our Parish Pres. Billy Nungessor hold up!



wishing you all the best of luck and please be safe
Member Since: September 19, 2005 Posts: 2 Comments: 4266
I made a forecast for Isaac
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first of all the gfs initialized at 991 mb....
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Oh This suspense of the storm is terrible. We are bunkered down at the top of Plaquemines Parish in Lousiana right below New Orleans. Praying all the prep work done by the Core and our Parish Pres. Billy Nungessor hold up!
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Member Since: July 12, 2007 Posts: 0 Comments: 6092
Quoting GTcooliebai:
Anyone else having problems running the GFS past 54 hrs.?


YES HERE IN ALLAN HUFFMAN´S
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Quoting CaneHunter031472:
If Isaac is not a Hurricane in the morning I really doubt it will ever reach that sataus before landfall.
HH find 78 mph winds? thought I saw that reported, but didn't see it all and maybe that wasn't surface?
Member Since: August 28, 2005 Posts: 0 Comments: 153
1959. FOREX
Quoting Scotth:
Does anyone see Isaac quietly sneaking its way north recently?


yup
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Quoting Scotth:
Does anyone see Isaac quietly sneaking its way north recently?

Still looks like a WNW/NW motion to me and recon fix shows a WNW movement(293 degrees).
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Quoting dipchip:
Seems to me Isaac is going to slide along the South shore of La. and go into Cameron south of Lake Charles La.


Dip, I've had Mud Lake, swest of Grand Chenier picked out for days, but thinking now with some strengthening he's going to keep pushing poleward.

SFC MAP


I think we're about to see him head nw, almost due north fairly quickly - midday tomorrow.
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1956. K8eCane
i hope all my friends stay safe down there. aas a rule of thumb, never underestimate a tropical system.
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1955. Scotth
Does anyone see Isaac quietly sneaking its way north recently?
Member Since: August 4, 2004 Posts: 0 Comments: 23
If Isaac is not a Hurricane in the morning I really doubt it will ever reach that sataus before landfall.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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